The long term goal of this research is to determine which visual cues are processed by amacrine cells to thereby provide a physiological/morphological classification scheme for these cells. The central theme of this proposal is to determine basic cellular properties and localized interactions of amacrine cells. The basic method used is intracellular recording from neurons in the superfused, isolated retina-eyecup preparation of the rabbit. Physiologically-characterized cells are subsequently labeled with intracellular stains, such as neurobiotin, to determine their soma-dendritic profiles. The specific aims are to determine: (1) the response properties expressed by amacrine cells and to correlate these with their cellular morphologies; (2) the different sites (somatic vs. dendritic) at which spikes are generated within amacrine cells and how these spikes are propagated within their dendritic arbors; (3) what role active propagation of synaptic inputs plays in shaping the receptive fields of amacrine cells; (4) whether AII amacrine cells show visual responses in the light-adapted retina, thereby subserving cone vision; (5) the pharmacologic mechanisms underlying light- and dark- induced changes in coupling and receptive field size of horizontal and AII amacrine cells; and (6) whether the correlated spike activity of neighboring alpha ganglion cells is due to coupling between alpha ganglion cells, possibly mediated by coupling with amacrine cells.